The present invention generally relates to computer communication networks, and more specifically to a method and apparatus for forwarding information frames from one network--particularly a token ring network--to another in a multiple network communication system. The present invention is an attempt to replace or improve upon so-called "brute force" methods of source routing bridging which require storage of frame information and more than one scan of that information for deciding if the frame is to be forwarded to another network, thus increasing processing time and circuit complexity. In source routing bridging the source of the frame, such as a workstation attached to a network, determines where the frame is to be routed (in contrast to transparent bridging, where the bridge determines where the frame is to be routed).